Electric motor and method of operating same



'March 1, 1932. s, plLLSBURY 1,847,441

ELECTRIC MOTOR AND METHOD OF OPERATING SAME i e April 1926 2 Sheets-Sheet l ff My f/ZWAZ7; W

March 1, 1932. E. s. PILLSBURY 1,347,441

ELECTRIC MOTOR AND METHOD OF OPERATING SAME Eiled April 2 1926 2 Sheets- Sheet 2 2'6 ,IGOVERNOR I STROKE |SHOF?TC|RCUIT!NG l STROKE IBRUSH-LlFTING J STROKE lBRusH {TRAVEL w, WALEZJ Patented Mar. 1, 1932 PATENT OFFICE EDWIN S. PILLSBURY, OF ST. LOUIS, MISSOURI ELE'c'rfuc Moron AND METHOD or OPERATING SAME 1 Application filed April 2,

This invention relates to improvements in electric motors and methods of operating same, and more particularlyto motors having speed controlled short circuiting and brush lifting means. 7 he motor disclosed in United States Letters Patent 1,130,017, granted to me on March 2', 1915', is typical of the motors of this class in which there is simultaneous sort circuiting and brush lifting. In that patent, thebrush release,or brushlifting means, comprises a parallel link motion which results in a like ratio of'movement between the short circuiting elements and the brush lifting elements;

and'inasmuch as only the travel, or movement, of the governor actuated, or speed controlled, element is utilized in effecting the short circuiting,-there is very limited brush movement, and, as a consequence thereof, a relatively short brush life and a requirement for relatively short brush lengths.

Theprimary obj ect of the present inven tion is toconstructa motor having speed controlled short circuiting and brush lifting means which operate to complete the short circuiting prior to the lifting, or releasing of the brushes. 1 1 Another object is to construct a motor having short circuiting means and a brush lifting, or releasing, means and a governor,.or. speed controlled device, in such manner as to utilize a portion of the movement, or travel, of the speed controlled device to effect the short circuitin'g and the r-em'ainder of the movement, or travel, of said device, together with the increased energy produced by the governor, to affect the brush lifting, whereby the short circuiting and the brush lifting are performed as distinct, independent, successive and'non-concurrent operations, and the increased energy, at substantially the limitof the governors movement, is available to lift the brushes. V

A further object is to construct a motor, having short ci-rcuiting means and b-rushlifting, or releasing, means, whose functionate movements are affected by a governor, or

speed controlled device, and in" which a mo-.1

tion increasing gear operates insuch manner as to utilize a portiomonly, 'ofth'e movement,

1926. Serial No. 99,258.

or travel, of the governor controlled device to complete the short circuiting, wholly prior to any movement of the brushes, and to cause the motion increasing gear to utilize the remainder of the movement, or travel, of .5 the governor controlled device to move the brushes a relatively greater distance than the remainder of the movement, or travel, of the governor controlled device, resulting in a greater length of brush life and a wider range .0 of brush lengths.

A further object of my invention is to construct a brush holder having a substantially ring-shaped body, which may be readily, de-' tac'hably and adjustably secured within the as motor shell, or casing, and which is provided on its periphery with facets, or tables, upon which the brush holders, brush springs and brush lifting means are assembled and detachably secured and .which lifting means 10 comprises a link motion consisting of bellcranks of unequal arm lengths.

' A; still further object of my invention is to provide a method of operating an electric motor, having automatic short circuiting and [5 brush lifting means, which consists in effect ing the completion of the short circuiting wholly prior to the liftingof the brushes.

My improvements consist in the novel construct-ion, arrangement and combination of 80 parts, as hereinafter fully, clearly and concisely described, definitely pointed out in my claims and illustrated by the accompanying drawings in which Fig. 1 is an end view of my improved 85 brush holder.

Fig. 2 is a plan view of the brush holder.

Fig. 3 is an elevation of a fragment of a motor, with parts broken away and in section, showing the short circuiting means and brush lifting means inv normal running position.

Fig. 4 is a diagram showing the shortcircuiting means as shifted to short circuiting position and the brushes in contact as upon a partial movement of the speed controlled device.

i Fig. 5 is a diagram showing the short circuiting means in short circuiting position and mo the brushes fully lifted as upon a lull movement of the speed controlled device.

Fig. 6 is a chart illustrating the comparative strokes and brush travel.

Referring to the drawings, A desi nates the shell, or casing; 13 the motor shaft; C a bearing for the shaft; D the armature; E the short circuiting ring; F the commutator; G the short circuiting segment; H the governor actuated element; and I a threaded projection of the bearing 1, all of which may be, or are, of ordinary and conventional construction and arrangement.

The brush holder J best shown in Figs. 2 and 3 comprises a substantially ring-shaped body 4, having at its outer end an internally threaded flange 5, which, when threaded to the recited projection I, constitutes the sup port for the brush holder as a whole. Facets 6 are formed on the periphery of the body 4 upon which are assembled the retainers 7 for the brushes 8. On, and preferably formed integral with, the body are the posts 9, for the support of the brush-springs 10. The ring preferably carries an index arm support 11, preferably formed as an integral extension of the ring.

Carried on each brush retainer is a bellcrank 12 for engagement with a brushspring; a bell-crank 1" for actuation by the recited governor actuated element II and a link 14. connecting the bell-cranks 12 and 13. In the body l are openings 15 (Fig. 3) through which the inner ends of the bellcranks 13 project.

The short circuiting segment G, as shown, is carried on a barrel 16, which surrounds the motor shaft B, and moved in a functioning direction by the governor elements II and restored to normal running position by a spring 17. Carried at the outer end of the barrel 16 is a loose-ring 18 which directly engages the bell-cranks 13 to ellect release of the brushes.

In Fig. 3, the short circuiting segment G is in contact with the short circuiting ring E, the brushes 8 are in contact with the commutator F, and the governor cont-rolled ele ments II are in their contracted positions which is the normal starting condition of the motor.

In operation, when the motor reaches a predetermined speed, the governor actuated elements H move the barrel 16, carrying the short circuiting segment G, to short circuiting position, relative to the short circuiting ring E, as shown in Fig. 4, prior to any move ment of the brushes 8; a continued movement, of? the barrel for the relatively short remainder of its travel effects the release of the brushes from the commutator, as shown in Fig. 5, by means of the motion multiplying gear, the bell-cranks 12 and 13, and the link 1.4.

I claim 1. A brush holder having a brush release including a multiplying gear comprising a pair of bell-cranks, each of said cranks having arms of unequal length, and a connecting link having a pivoted connection with a shorter arm of one of said cranks, and with the longer arm of the other of said cranks.

2. A brush holder including a brush spring, and having a brush release including a multiplying gear comprising a pair of bell cranks, each of said cranks having arms of unequal length, and a connecting link having a pivoted connection with a shorter arm of one of said cranks, and with the longer arm of the other of said cranks, the shorter arm of one crank being disposed for engagement by a speed responsive actuator, and the longer arm of the other crank being in operative engagement with said brush spring.

3. In a motor, the combination of brushes, a brush holder, brush springs, a speed responsive means, and a ointed connection between said means and one of the brush springs, and including a plurality of angulate levers, each having arms of unequal length, the levers being pivotally connected together, and being fulcrumed on the brush holder.

4. In a motor, a shaft, a brush spring, spring-release mechanism comprising an element movable along the shaft responsively to the motor speed, a brush-releasing arm consisting of a bell-crank lever, a second lever adapted to be moved by the speed responsive element, and in operative engagement therewith only near one limit of its accelerating movement, said levers being associated in motion increasing relation, and a link connecting the levers.

5. In a motor, a brush spring, a spring release mechanism comprising a governoractuated element, a bell-crank lever disposed for operative engagement by said element only near one limit of movement of said element, said lever being operatively free of said element over other portions of its path of travel, and a plurality of other levers as sociated with the bell-crank lever and adapt ed to translate a relatively limited, final movement of the governor-actuated element into a relatively greatmovement of one arm of the bell-crank lever.

63. In a motor, the combination with a brush holder, brushes, and a speed responsive element, of a plurality of operatively connected levers, one of which is pivoted to the brush-holder and adapted for actuation by the speed-responsive element, another of the levers being associated with a brush-spring, each of said levers having arms of unequal length set at a substantial angle to each other, and a connecting element associated with unequal arms of said levers.

7. In a motor having a brush holder,

brushes, and springs therefor, a speed-controlled actuator, and jointed members carried by the holder, operatively' connecting the actuator and each of the brush springs; one of said members constituting a lever having a long arm and a short arm and adapted thereby to effect a brush-spring movement at a rate in excess of the movement of the actuator, said short arm having an operative connection with the actuator only at the time of its final accelerating movement.

8. In an electric motor, including brushes, brush springs, a shaft, a sleeve movable along the shaft, responsively to motor speed, short circuiting elements carried by the sleeve, brush-spring releasing mechanism adapted to be actuated by the sleeve and comprising a spring actuating arm, a lever spaced substantially from said sleeve at sub-normal motor speeds, and adapted for engagement thereby only as the motor approaches its normal operating speed, and a link connecting said arm and lever in motion increasing relation; said sleeve and mechanism comprising means providing a substantial interval of movement of said sleeve between its initial short circuiting and brush lifting movements, u on acceleration of the motor.

DWIN s. PILLSBURY. 

